Duty to a Melody
by The-Black-Knight673
Summary: Augustus, a Sternguard Devastator, is sucked into a warp rift and dropped right in Equestria! His body changed from the might demi-god Astartes, to a somewhat muscular unicorn stallion. With no way of figuring out a way back to his ship, the veteran Astartes decides his best course of action, would be to try and "blend in"... Running into a certain chellist to help him with this.
_**The Black Knight simply sat in his chair, right leg crossed over his left, while Silver Star was busy drawing something on a piece of paper. "Figured this will be a fun little crossover story… And by crossover, I do not mean with just MLP and Warhmmer 40k." He smirked a bit, leaning more into the chair hands clasped together, before his gaze went to a clock. "Time is almost up… I wonder how much longer you all can stand waiting, hmmm?" He chuckled a bit, waving goodbye.**_

 _ **Chapter One**_

Within the armory of an Ultramarine Battle Barge, a single Sternguard Devastator Marine performed the routine wear and tear maintenance of both his master-crafted Aegis Armor and decorated lascannon. Laying on the prep bench, next to the veteran Ultramarine, sat a personal copy of the Codex Astartes. Playing throughout the armory's intercom, to help with both his concentration and relaxation, classical music echoed all around the confined room. He let out a content sigh, each movement he made in sync with the music's tones.

Augustus enjoyed moments, like these, where he ritually cared for the very lascannon he had been given on his first day as a Devastator Maine. It brought some normality to his ever changing, and hectic, life filled with both danger and death. With this, he could be reminded that _something_ will always remain the same for him.

The Ultramarine did a quick diagnostic check, allowing the lascannon to link up with Augustus' helmet for sight adjustments. Once that step was completed, he leaned over and used his armored finger to help him scan through the steps of proper Lascannon Maintenance. Like the several thousand times before, Augustus had done it perfectly, giving an approving nod.

"Brother Augustus?" A voice called out, making him look up to see two other Stengards approaching hi.

Augutus laid the lascannon across his lap, tilting his head to the side. "Yes, brothers? How can I be of assistance?" He asked, he two stopping just in front o him.

"We were wondering if you will be joining us within the Chapel? The Chaplain will be giving his sermon soon." The right one asked, as the Devastator shifted uncomfortably. Ever since his tour within the Deathwatch ended, Augustus had not been so devoted like the rest, one can only be blind o so much within the galaxy… And he no longer treated things like your average Ultramarine.

"Unfortunately, I cannot, brother. I still have much to do, before the machine spirits of my armor ad weapon are satisfied… They are quite old, and require much maintenance." He lied, trying to play off the idea he was not finished yet.

The other two Sternguards nodded to him, understanding that such preparations always take priority over everything. "Of course, brother. We shall pray extra for you… The travel through the Warp is a dangerous thing, and we shall require all those faithful to the Emperor, for safe passage."

Augustus gave a nod, placing a hand gently on to the lascannon. "Do not worry, brother. The Emperor shall hear our prayers, even while we do the everyday tasks, such as weapon and armor maintenance." He noted, the other two nodding to this fact.

The two Sternguards gave one last nod, before the entire Battle Barge suddenly shook, causing them to look around. "We best be going. We will also give the Chaplain your regards, brother." Augustus gave a nod, as his brothers left the armory.

The Sternguard Devastator lowered his head, shortly after the two had left. Augustus was, by no means, a heretic or a faithless. However, he just could not find himself praying to the God-Emperor of Mankind, so easily anymore. It pained him to think of such a thing, an Ultramarine not holding the faith expected from the Sons of Guilliman. If any were to find out about this, the Sternguard would be forever shamed, but it cannot be helped... He has seen so many horrors within his service to Deathwatch. It would make many wonder about their faith, if the Emperor truly _was_ watching over them.

The Sternguard placed a hand more on to his lascannon. "Even if I cannot count on my prayers… I can always count on you, old friend." He said, Augustus' ceramite clad fingers tracing every inch of the long range heavy weapon. His helmeted eyes went to the honor seals and kill marks adorning the weapon, smiling. The Sternguard truly felt honored to wield such a long lasted weapon. In any comparison, by how Augustus cares for the devastating weapon, one would say he treats it like his very own child.

Out of nowhere, the classical music suddenly fell silent, being replaced by blaring alarms soon after. "All hands, to battle stations! All hands, to battle stations! This is not a drill. I say again, this is not a drill! The gellar field have failed! All combat units, prepare for possible daemon incursions or random warp rifts opening within the ship!" One of the bridge's crewman announced over the vox.

Augustus narrowed his helmeted eyes, quickly sanding up and readied the venerated lascannon. If there were to be a daemon incursion, he would not be the ideal choice of combatants. However, he could be useful for more opened areas within the ship, or picking off heavily armored foes. The Sternguard hoisted the lascannon in one arm, and reached for his personal copy of the Codex Astartes…

Then, just as the Sternguard was about to pick up the long venerated manual, a warp rift suddenly opened up within the armory! "What in the Emperor's Name!?" Augustus shouted, looking towards the tear in reality.

The rift suddenly grew, in size, starting to suck in everything around it like some miniature black hole! The Sternguard grabbed on to the bolted down bench with one hand, and kept a tight grip on the lascannon with the other. His gaze went to the tear, feeling the pull from it and his grip on the bench starting to place far too much strain on his shoulder and arm.

Not knowing what possessed him to do so, Augustus used the hand with his lascannon to take aim at the rift. The uplink between the weapon and his helmet instantly came on line, allowing the Sternguard's targeting system to increase by tenfold. But he could not target a thing within the rift itself, no cause to this strange pull. Going on a limb, and a classic tactic of the Space Wolf that was in his Deathwatch Squad, Augustus fired at the rift! The high intensity blast, which had enough power to take out Predators, searing into the rift.

The inside of the rift started to swirl, where the lascannon struck, and shift from a purple color to a white light. The rift's pull intensified, forcefully ripping Augustus from his grip on the bench! The Sternguard lost the hold on his lascannon, flailing to grab on to something,as his weapon was the first for the new rift to claim… To his despair, Augustus failed to gain a hold on to anything, being sucked into the rift next… Followed by a pack and his personal copy of the codex.

Almost like it had been waiting to claim him, the rift closed shortly after Augustus, and his personal belongings, went through. The Battle Barge's gellar field coming back on line, none the wiser that they were short one Astartes.

 **-Equestria, White Tail Forest-**

A rift opened up, just shy of a lake's bank, and quickly dropped a decent sized unicorn stallion on to the ground. The unicorn groaned, shaking his head, before slowly sitting up. He rubbed the side of his head, just as a pair of half glasses landed on to his blue muzzle, causing him to raise an eyebrow. But, before he could think anything about it, a large book landed on to his head, forcing the stallion back on to the ground, followed by a saddle bag.

"Ooooooowwww…" Augustus groaned, rubbing where the book struck him, before realizing something. "Wait… No armor? Hoof, instead of hand?" The Sternguard looked towards the lake not far from him.

Walking up to its shores, he looked at the reflection and gave a slight gasp. Augustus noticed a decently sized unicorn stallion staring back at him, instead of the Sternguard Ultramarine. His coat being a blue hue that shared with is armor's own, with a matching white mane and tail. His eyes, behind the half glasses, were a shining emerald color that were brought out more by his coat and mane color. Though, catching the glimpse of something further back, Augustus turned to see some picture displayed on both sides of his flank.

The image was the Ultramarine Insignia with a sniper's crosshair taking up the center. "Good to know that _something_ remained the same." He said, calmly, before glancing around. "Now… Where is my lascannon? I know it is close by, I can just feel it." Augustus began to look around the surrounding area, his abnormally long horn giving of a sky blue glow. "I can feel it charging to fire, which is strange, I wonder why that-!"

His horn shot a beam of concentrated sky blue energy, making the stallion go wide eyed. The attack struck a large trunked tree, creating decent sized burning hole where it made contact.

Augustus just stared at the smoking hole, before crossing his eyes and looked up at the smoking horn. "Ah… There you are." He smirked, before walking over to his book, staring at the codex and his hoof. "I wonder if the codex says anything about this?"

Sitting down on his flank, the stallion used his hoof to open the codex and turn the pages within. Many would say that Augustus was acting far to calm for such a situation… Normally, this would be have made him go into some form of hysteria, if he had not been part of the Deathwatch and his squad ended up on some rather… Strange ending missions. The horrors and cruel fates allowed the Sternguard to steel himself, so that he could make the needed decisions with a calm mind.

The stallion smirked, as he turned to a section on Warp Rift Abnormalities and planets they could lead to. "Ah, here we are. Let's see, warp rifts could spontaneously appear when a ship's gellar field fails…" He started to mumble the other tid bits of information, trying to skip ahead. "Ok, so warp rifts, due to their unpredictability, their outcomes could have strange side effects, including bodily alterations." Augustus looked at himself, then back at the book. "That's an understatement of the millennia." He scanned further into the book, reading the passages about possible changes to one's body, until he reached the conclusion. "But do not lose heart, young Astartes… Studies show that the effect could only be planetary. Leaving said planet can nullify the effects."

His eyes went wide, staring at the codex, looking to see if there is more on the matter… Or if he at least missed something else, when skimming over bits of information.

"That can't be it? There has to be more to it!" Augustus kept turning the pages, before placing his face into the book. "By the Emperor… Talk about terrible luck!" He pulled his head back up, a deadpanned look on the stallion's face. Augustus was about to say something, further, about how terrible his luck had been… When the sight of a cyan pegasus zooming overhead caught the stallion's attention. "Hello, what's this?"

Augustus attempted to follow the pegasus, with Codex in hoof, but noticed that the attempt was rather difficult. With a raised brow, he looked at the Codex, then back at the strange saddlebag that appeared with him. It was strange, how said bag was a perfect fit for him. His gaze went up to the strange horn on his head, which the former Astartes assumed to be his lascannon. He concentrated a bit, aiming it at a nearby branch, and shot out a thin beam of sky blue energy, snapping the branch in two.

He raised a brow, knowing how unicorns were known for being magical creatures, using their horns as focal points. " _I wonder…_ " Augustus thought, before concentrating on picking up the saddlebag, a completely one eighty from the display he just gave, trying to envision himself picking it up. The stallion's horn started to glow with the same sky blue energy from before, the saddlebag being incased within the same energy.

Slowly, the saddlebag started to float off of the ground, and pulled towards him. It hovered over his back, for a few seconds, before settling down on to him. The aura left majority of it, but stayed on the saddlebag's straps and buckles. Once they were connected, and tightened down, the stallion looked back at his handiwork and smirked.

"That's rather practical, and could be useful down the road." He stated, his horn lighting p again, but this time to place the codex into the bag. Once it was secured, and hidden, Augustus gave a nod. "Alright then! Now to see where that pegasus raced off to!" With that, he trotted off towards the direction that the cyan pegasus flew in.

 **-Ponyville Outskirts-**

Augustus, honestly, could not believe the sight he was seeing right now… A small town of colorful, cartoonish, sentient equine! He hid just outside of the town, watching them from the wood line's dense cover. The stallion had spent the last hour performing recon and information gathering, ever since he arrived and saw the pegasus with five other mares.

To say that he was completely dumbfounded, by what was there, would be an understatement. Some of the things he witnessed them do, were logically impossible! Such as controlling the weather itself. There was even a pink mare, who _seemed_ normal to Augustus, that had the ability to disappear and then reappear at will! He was left with a single conclusion, on how to approach this situation, for now.

"Best go down there, and observe first hand." Augustus decided, with a nod, and took a step towards the small town. He knew it would be best to stay silent, and not try to interact with the locals, while also attempting to blend in with the crowd. Normally, this would be extremely difficult for an Astartes, but Augustus' new body made it much easier for him to accomplish.

Moving through the small town, giving an occasional friendly smile here and there, along with keeping his glasses up, the stallion kept a sharp ear and eye out. He needed to gather more information, such as names and common knowledge, in order for him to integrate into their society easier. Though, from what he could tell about their naming system, there was nothing normal about it! It seemed like they often used a two-part naming system, but everything else seemed so random! Some names were completely unrelated or very stereotypical of such a thing. Like one group of ponies being apple farmers, and their names having something to do with the very apples they farm. Or this one pinkish unicorn mare whose name being "Sparkler" and she was some kind of organizer…

" _I need to take a break._ " The stallion thought, walking to the town's park and sitting on to the stone bench. Removing his glasses, Augustus rubbed his temples. " _I cannot shake the feeling that this will be the biggest headache of my entire life… And that s saying something, when trying to get a Blood Angel and a Space Wolf to get along, not to mention a Salamanders and a Black Dragon!_ " With a sigh, the stallion leaned back on to the cold stone and looked up at the clear sky. " _Best think of a name, before one of these ponies gets smart and actually ask me for it._ "

The stallion went into deep thought on the subject. It had been obvious, after the fourth name he head, that his real name would not do. As for what he would call himself/ Now that was the greatest question, of all time. From what Augustus could figure out about their naming system, majority had something to do with either their family, 'special talent', an aspect about them, or where they lived. Glancing down at his 'cutie mark', as he heard they were called, and then to his horn… The unicorn stallion wondered if he should name himself after his venerated weapon.

" _No, too cliché._ " He scoffed at the idea, but then an idea hit him. His color design, including the eyes, mixed with the amount of power behind a simple beam from his attacks reminded Augustus of the beautiful, yet powerful, supernovas found in space. Then there was the fact that his attack had specifically formed into a highly concentrated beam of precise energy… _Just_ like his devastating lascannon. A sly smirk appeared on his muzzle, he knew _exactly_ what to call himself now.

But, his train of thought got interrupted by a flyer, slapping into his face. With a curse, Augustus pulled the paper off and looked down at it, with a raised brow… The picture was of a gray earth pony mare, with a rather dark gray-black mane and tail. Around her neck was a white collar and pink bowtie, almost like it was signifying formal wear. Her cutie mark was a pink violin treble chef which, mixed with the chello in her hooves, allowed Augustus to believe that she was some classical musician.

"Octavia Melody, performing tonight at the Ponyville Schoolhouse Charity Event. Do not miss out on her expertly performed classical styled music?" He read, out loud, with a smirk. " _Finally, something familiar and normal._ " Augustus used his magic to roll the flyer up, and placed it within his saddlebag. " _And a Charity Event… It would be uncharacteristic if an Ultramarine does not show up to such a thing, and do what he can to help._ " The stallion quickly got up, having his saddlebags placed on to himself. " _Regardless, though, best make sure I look presentable… Do not want_ anypony _to think less of me at such a thing._ " With that, he went off to prepare for the night's festivities.


End file.
